1. Field of Art
This invention relates to decoration of cylindrical articles and in particular to shrink wrapping plastic film against cylindrical articles such as can bodies.
2. Brief Description of the Prior Art
In the decoration of can bodies, the most commonly used techniques are off-set printing with ink as is typical for beer and beverage cans, and paper labeling as is typical for food cans. Although off-set printing is widely used, an alternative technique is desired which would use less heat energy and produce less air pollution. Typical off-set printing systems require a base coat and two baking operations to dry the base coat and the ink and the printed cans. Printing uses considerable heat energy in such baking operations, can cause objectionable air pollution when hydrocarbon solvents are driven off during drying, and is time consuming. Off-set printing equipment is also expensive and the off-set printing is one of the primary causes of scrap cans in can manufacturing lines. Paper labels are acceptable for food cans, but are vulnerable to damage or loss, and are not suitable for beer and beverage cans which are exposed to water.
Plastic labels are known, but there has heretofore been no fast way of applying such labels on cans at the speeds typical of most can making lines. The prior art such as U.S. Pat. Nos. 3,110,554 and 2,878,628 discloses techniques in which articles are shrink wrapped with plastic labels one article at a time.
The prior art is lacking in a disclosure of a high speed technique for applying plastic labels on articles such as can bodies.